Ghouls

Ghouls are strange, ape-like creatures that seem to sense wounded creatures from miles away. They prefer to feed on still-living flesh, but are not powerful enough to take on many prey at once, so they also feast on animals that have injured themselves. These beasts make no distinction between wounded animals and wounded humans. Often, field hospitals must be guarded at night, for ghouls have been known to slip inside and attack the wounded men. Most soldiers are deathly afraid of being found in a weakened state by a ghoul, and ghouls following an army are seen as a very bad omen.
More rarely found are stronger, more intelligent versions of a ghoul, known as an alghoul.